I have a quattro + fronius microgrid that's not working very well (tried on output of quattro, tried on input... it's limiting the hell out of fronius output), so i'm currently using the fronius smart meter to limit injection to grid (undesirable as I pay for export).
But next week, I will install another 3Kw system with Huawei inverter (this will also be grid-tied and approved by the power co. for export).
Below is the diagram that I though on using. Basically just inserting the 3Kw Huawei inverter between the grid and the smart meter.
After this new installation, I can inject a bit more to grid from the fronius, or victron, as long as anti-islanding is obtained.
PS - my victron is acting up under heavy loads ( i need to warranty is someday...) from battery, so I am forced to user the EV charger directly form Grid or whenever I do have solar enough to discharge from battery less than 2-3kwh, hence the location.